I would add to this list, buildings and units that encourage resident diversity. As in, a diversity of ages, household size, economic class (and ideally also race/ethnicity/country of origin). Organically this means a mix of “luxury” and “budget” housing, unit sizes (studio through three bedroom at minimum), building ages and designs, target demographics for shops (e.g. upscale shopping alongside budget grocers), and community amenities (e.g. schools and senior centers). In a pinch subsidized housing can help with integration, but it’s a limited and costly solution.

That they were. I was so confused as a kid, because I was a big fan of donuts but had never seen one with a rectangular hole coming out the side (how would that even work?)